/*
 * Copyright (c) MuleSoft, Inc.  All rights reserved.  http://www.mulesoft.com
 * The software in this package is published under the terms of the CPAL v1.0
 * license, a copy of which has been included with this distribution in the
 * LICENSE.txt file.
 */
package org.mule.runtime.core.util.counters.impl;

import org.mule.runtime.core.util.counters.CounterFactory.Type;

public class InstantRate extends AggregateCounter {

  private double firstTime;
  private double lastTime;
  private double value;

  public InstantRate(String name, AbstractCounter base) {
    super(name, Type.INSTANT_RATE, base);
  }

  @Override
  public double nextValue() {
    if (firstTime == 0 || firstTime == lastTime) {
      return Double.NaN;
    } else {
      return value / (lastTime - firstTime) * 1000.0;
    }
  }

  @Override
  public void doCompute() {
    firstTime = lastTime;
    lastTime = System.currentTimeMillis();
    value = getBase().nextValue();
  }
}
